Hareittr: Pennaria tiarella and Tubularia crocea. 
PLATE, 9. 
Tubularia crocea. 
All figures are from blastulae, or from embryos forming the germ layers, 
and show the double nuclei characteristic of those stages. Corrosive-acetic, 
iron hematoxylin. X 2250. 
Fig. 
Fig. 
Fic. 
Fig. 
Fia. 
Fig. 
Fig. 
Fia. 
Fig. 
rake 
72. 
73. 
74. 
75. 
76. 
rifle 
78. 
Primitive entoderm cell in resting condition. 
Primitive ectoderm cell in resting condition. 
Primitive entoderm cell in resting condition, showing the persistent 
interzonal filaments of the preceding cell division. 
Entoderm cell. Spindle of an approaching division forming, and 
interzonal filaments of the preceding division still present. 
Ectoderm cell with the chromosomes formed independently in the 
two parts of the nucleus. 
Entoderm cell similar to Figure 75, but having two centrosomes and 
asters. 
Portion of an ectoderm cell showing recently completed nuclear 
division, interzonal filaments still visible and each daughter nu- 
cleus composed of two vesicles. 
Polar view of chromosomes in daughter plate, not in two groups. 
From a cell early in the formation of the germ layers. 
79a-79e. Polar views of five equatorial plates in the division of ectoderm 
and entoderm cells of the germ layers, showing arrangement of 
chromosomes in two groups. 
